"The Brexiteers wanted out of Europe but they had no plan for the day after or any other day in the future," said Ian Blackford, a Scottish National Party lawmaker who supported the motion for the debate, in parliament's second debating chamber, which does not have the power to change the law.

In the June 23 vote, 51.9 percent, or 17.4 million people, voted to leave the EU while 48.1 percent, or 16.1 million people, voted to stay in the EU.

Within two days, the petition had garnered 2 million signatures, but prospects of a second referendum appeared unlikely.

“Politically, the notion of re-running a referendum on membership is unimaginable,” Anand Menon, director of the UK in a Changing Europe, a London-based independent body of experts, told The Christian Science Monitor at the time. “I just don’t think it has legs, bearing in mind the level of hypocrisy that would be required on both sides.”

"Brexit must mean Brexit and it is up to every red-blooded democrat, no matter which side they were on before the result was known, to accept the clear electoral verdict and to pull together to deliver it as best we can," said John Penrose, a Conservative Party lawmaker who opposed the motion to debate the referendum.

David Lammy, a Labour lawmaker, said during the debate that the meaning of Brexit was unclear as were what the terms would be for Britain to have access to the European single market.

The Brexit result, which historians say compares to the 1991 fall of the Soviet Union in its significance, unleashed immediate political and financial market turmoil in Britain.

The vote has also raised questions about the future of Britain and post-World War Two European integration, though the economic impact has been less negative than was predicted by remain campaigners.

Prime Minister Theresa May, who did not support leaving, says Brexit means Brexit and the vote will be respected.

But at least seven lawsuits have been brought to force the government to accept that parliament should decide whether Britain should trigger Article 50 of the Lisbon Treaty, the formal exit process, rather than the prime minister. (Reporting by Guy Faulconbridge, Editing by Elizabeth Piper)